Fluid tight mounting of crystal in watch case

ABSTRACT

A crystal is secured in a watch case in a fluid tight manner by means of a bushing of compressible semirigid material such as nylon. The bushing fits into an annular recess at the front of the watch case and is pressed tightly against an annular wall of the recess by a compression ring which fits into an inner portion of the bushing and overlies the peripheral portion of the watch dial. The crystal fits into an outer portion of the bushing and is positioned axially by the compression ring. A tension ring surrounds an outer portion of the bushing and presses it tightly against the periphery of the crystal to provide a fluid tight seal.

United States Patent [191 Siegrist FLUID TIGHT MOUNTING OF CRYSTAL IN [111 3,817,025 [4 June 18, 1974 [54] 390,162 3/1965 Switzerland 58/90 R WATCH CASE [75] Inventor: Edward Louis siegl'ista Cologny, Primary Examiner-George H. Miller, Jr.

Switzerland Attorney, Agent, or Firm-Robert E. Burns; Emman- [73] Assignee: Ed Wenger S.A., Geneva, Lnbato Switzerland [22] Filed: Sept. 29, 1972 21 App]. No.: 293,675 [57] ABSIRACT A crystal is secured in a watch case in a fluid tight [30] Foreign Application Priority Data manner by means of a bushing of compressible semi- Sept. 30. 1971 Switzerland 14384/71 rigid material Such as nylon- The bushing fits into an annular recess at the front of the watch case and is 52 us. Cl 58/90 R Pressed tightly against an annular wall of the recess y 51 rm. Cl. G04b 37/08 a compression ring which fits into an inner portion of [58] Field of Search 522/88 R, 90 R, 91 the bushing and overlies the Peripheral portion of the watch dial. The crystal fits into an outer portion of the 5 References Cited bushing and is positioned axially by the compression UNITED STATES PATENTS ring. A tension ring surrounds an outer portion of the bushing and presses it tightly against the periphery of 2,609,655 9/l952 Vermot 58/90 R the Crystal to provide a Seal.

FOREIGN PATENTS OR APPLICATIONS I 332,896 9/1958 Switzerland 58/90 R 10 Claims, 1 Drawing Figure 8a 3 )2 j l y l a fi v 3 l l/ FIELD OF INVENTION The present invention relates to the mounting of a crystal in a fluid tight manner in the case of a watch and pertains particularly to the fluid tight mounting of inorganic watch crystals formed of glass or sapphire.

BACKGROUND OF INVENTION Several arrangements for providing a fluid tight mounting of a watch crystal are presently known. For the most part these constructions utilize'the lateral compression of a gasket between the crystal and the lateral wall of a recess provided in one of the elements of the watch case.

The best known means of obtaining a fluid tight mounting of a watch crystal formed of transparent plastic is to force the crystal into a recess in the watch case, fluid tightness being obtained by the lateral compression of the plastic crystal against the surrounding wall of the recess. The fluid tight joint between the plastic crystal and the recess of the watch case can be improved by means of a tension ring fixed to the interior of the crystal and compressing an annular border portion of the crystal against the lateral wall of a recess formed in one of the elements of the case.

To obtain a fluid tight seal with an inorganic crystal, for example one formed of tempered glass or sapphire, a bushing of compressible material is compressed laterally between the crystal and the wall of a recess formed in one of the elements of the case. This compression is generally obtained by forcing the crystal-bushing assembly to the interior of the recess. This simple procedure generally gives satisfactory results with flat crystals of inorganic material but unfortunately it requires a relatively great height of the case which is not compatible with general esthetic considerations. Apart from considerations of appearance, an increasein the height of the case has the inconvenience that, when the case is formed of precious metal, it results in increasing the weight of the case and hence its cost.

SUMMARY OF INVENTION The arrangement in accordance with the present invention for fluid tight mounting of a crystal in a watch case comprising an annular portion provided with a resion element is inserted in the inner part of the bushing in a manner to compress the bushing against the surrounding wall of the recess. The crystal is positioned on the compression element in an outer portion of the bushing. A tension ring mounted on the watch case surrounds an outer portion of the bushing and compresses it against the periphery of the crystal. The compression exerted on the bushing by the element of compression and by the tension ring assure a fluid tight mounting of the crystal in the watch case.

The accompanying drawing represents by way of example a watch of which the watch case is provided with a mounting of the crystal in a fluid tight manner in accordance with the present invention.

BRIEF DESCRIPTIONOF THE DRAWING The single FIGURE of the drawing is a partial sectional view on the three hour-nine hour axis of a watch in accordance with the invention.

DESCRIPTION OF ILLUSTRATED EMBODIMENT The watch illustrated by way of example in the drawing comprises a movement I mounted in a case 2 by means of a mounting ring 3. A back 5 is removably secured to the case 2 by means of threads 5a. A fluid tight seal between the back and the case is provided by a gasket 4. A dial 6 on the front of the movement I is supported against a compression ring 7 fitting into a bushing 8 formed of compressible semi-rigid material such as nylon, Teflon, Delrin, I-lostaform C, plexiglass or polyvinylchloride. The bushing 8 is L-shaped in cross section with an axially extending portion 8a and a radially inwardly extending portion 8b. The bushing 8 fits tightly into an annular recess 2a in the case 2. The radially extending portion of the bushing 8 seats on a radial face of the bottom of the recess 2a while an inner portion of the axially extending portion 8a is gripped tightly between the axial wall of the recess 2a and the compression ring 7. The compression ring 7 is stepped to provide an outer portion of larger external diameter which presses the axially extending portion 8a of the bushing 8 against the wall of the recess 2a of the case and an inner portion of smaller external diameter which extends inside of the radial portions 8b of the bushing and abuts a peripheral portion of the dial 6. The inner peripheral surface 7a of the compression ring has an outer portion which is beveled and an inner portion which is cylindrical. An inorganic glass crystal 9 fits inside the outer portion of the bushing 8 and seats on the outer edge 7b of the compression ring 7. The crystal 9 is formed for example of tempered glass or of sapphire. A removable tension ring 11 has an undercut recess 11a which snaps onto a corresponding annular projection 2b of the case. The tension ring 11 has a tapered inner surface Ila which presses radially inwardly on the bushing 8, thereby pressing the bushing 8 tightly against the periphery of the crystal 9. The case 2, back 5, compression ring 7 and tension ring 11 are formed, for example, of metal although other hard, strong, durable material of attractive appearance can, if desired, be used. The bushing 8 may be clear or may be white or any desired color to provide an attractive appearance to the watch.

In this manner a tight seal between the crystal 9 and the case 2 is obtained by two lateral compressions of the bushing 8, the one being a lateral compression of the bushing 8 between the inner surface 11a of the tension ring 11 and the outer periphery of the crystal 9 and the other being a lateral compression of the bushing 8 between the inner periphery of the recess 2a of the case 2 and the exterior periphery of the compression ring 7. The connection between these two points of fluid tightness is assured by the bushing 8.

The construction in accordance with the present invention presents no particular difficulties in mass production which can be carried out in the following practical manner. The removable ring 11 is snapped onto the projection 2b of the case 2. Then the bushing 8, previously provided with the compression ring 7, is pressed into the recess 20 of the case 2. Then finally the 3 crystal 9 is pressed into the outer portion of the bushing The fabrication of the different parts constituting the construction in accordance with the invention for providing a fluid tight mounting of the crystal on the watch case likewise presents no particular difficulty and can be carried outby known means such as turning, milling, molding, casting etc. y

it will be seen that an advantage of such fluid tight mounting of the crystal of a watch is that it makes possible the replacement of a crystal of organic material with a crystal of inorganic material without the need of changing the height of the watch case. The fact that the height of the watch case is not increased is important for watch cases made of precious metal since an increase in height would mean an increase in weight and thus an increase in cost.

The finishing of a watch case in which a crystal is mounted in accordance with the present invention is simplified and can have a very significant aspect by reason of the fact that the case 2 and the tension ring 11 can be finished separately. It is thus possible to obtain contrast, for example by having the case 2 brushed and the ring 11 polished, without the finishing being complicated and costly.

While a preferred embodiment in accordance with the present invention has been illustrated in the drawing and is herein particularly described it will be understood that the invention is in no way limited to the particular construction of this embodiment.

What I claim and desire to secure by Letters Patent 1. In a watch having a case, a movement in the case and a dial on the front of the movement, said case comprising an annular part surrounding the movement and having a forwardly opening annular recess with an axially extending annular wall, an annular bushing of compressible semirigid material fitting in said recess and extending out beyond the adjacent surrounding portion of said annular part, a compression ring fitting in said bushing and pressing a portion of the bushing against said annular wall of said recess to provide a fluid-tight seal therebetween, a crystal positioned in said bushing outwardly of said compression ring, and a tension ring surrounding an outer portion of said bushing and press- 4 ing said bushing against the periphery of said crystal to provide a fluid-tight sea] therebetween, whereby said crystal is mounted in a fluid-tight manner in said watch case.

2. A watch construction according to claim 1, in which an inner edge of said compression ring rests on a peripheral border portion of the dial and said crystal rests on the outer edge of said compression ring.

3. A watch construction according to claim 1, in which said tension ring has an outwardly converging inner annular surface.

4. A watch construction according to claim 1, in which said crystal is of inorganic material which is rela- I tively incompressible as compared with said bushing of compressible semirigid material.

5. A watch construction according to claim 1, in which said crystal is-of organic material selected from the group consisting of nylon, Teflon, Delrin, Hostaform C, plexiglass and polyvinylchloride.

6. A watch construction according to claim 1, in which said annular part of the watch case has an upstanding rim around said recess and said tension ring has a cooperating part engaging said rim to secure said tension ring on the watch case.

7. A watch construction according to claim 6, in which said ring has an undercut outer wall and said tension ring snaps onto said rim to secure the tension ring on the case.

8. A watch construction in accordance with claim 1, in which said bushing is of angle cross section with a radial portion resting on the bottom of the recess in said annular part of the case and an axial portion extending out of said recess.

9. A watch construction according to claim 8, in which said compression ring has an inner portion of smaller external diameter fitting inside said radial portion of said bushing and an outer portion of larger external diameter engaging said axial portion of said bushing to press it against said annular wall of said recess.

l0. A watch construction according to claim 9, in which said compression ring has a bevelled inner surface framing said dial. 

1. In a watch having a case, a movement in the case and a dial on the front of the movement, said case comprising an annular part surrounding the movement and having a forwardly opening annular recess with an axially extending annular wall, an annular bushing of compressible semirigid material fitting in said recess and extending out beyond the adjacent surrounding portion of said annular part, a compression ring fitting in said bushing and pressing a portion of the bushing against said annular wall of said recess to provide a fluid-tight seal therebetween, a crystal positioned in said bushing outwardly of said compression ring, and a tension ring surrounding an outer portion of said bushing and pressing said bushing against the periphery of said crystal to provide a fluid-tight seal therebetween, whereby said crystal is mounted in a fluid-tight manner in said watch case.
 2. A watch construction according to claim 1, in which an inner edge of said compression ring rests on a peripheral border portion of the dial and said crystal rests on the outer edge of said compression ring.
 3. A watch construction according to claim 1, in which said tension ring has an outwardly converging inner annular surface.
 4. A watch construction according to claim 1, in which said crystal is of inorganic material which is relatively incompressible as compared with said bushing of compressible semirigid material.
 5. A watch construction according to claim 1, in which said crystal is of organic material selected from the group consisting of nylon, Teflon, Delrin, Hostaform C, plexiglass and polyvinylchloride.
 6. A watch construction according to claim 1, in which said annular part of the watch case has an upstanding rim around said recess and said tension ring has a cooperating part engaging said rim to secure said tension ring on the watch case.
 7. A watch construction according to claim 6, in which said ring has an undercut outer wall and said tension ring snaps onto said rim to secure the tension ring on the case.
 8. A watch construction in accordance with claim 1, in which said bushing is of angle cross section with a radial portion resting on the bottom of the recess in said annular part of the case and an axial portion extending out of said recess.
 9. A watch construction according to claim 8, in which said compression ring has an inner portion of smaller external diameter fitting inside said radial portion of said bushing and an outer portion of larger external diameter engaging said axial portion of said bushing to press it against said annular wall of said recess.
 10. A watch construction according to claim 9, in which said compression ring has a bevelled inner surface framing said dial. 